This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 20 |
| 3 | 616 |
| 4 | 99472 |
| 5 | 51647264 |
| 6 | 141339210560 |
| 7 | 1246922025235072 |
| 8 | 57999437806769246464 |
| 9 | 8698341593509034791428608 |
| 10 | 6878047564149771530513399567360 |
| 11 | 17535817352622479067842954626850351104 |
| 12 | 235723767989136531816996707739814303966793728 |